Draw an electron dot structure for the two molecules of C2H6O.
The correct answer and explanation is:
Correct Answer:
C₂H₆O has two possible isomers with different electron dot structures:
- Ethanol (CH₃CH₂OH)
- Dimethyl ether (CH₃OCH₃)
1. Ethanol (CH₃CH₂OH) Electron Dot Structure:
H H H H
| | | |
H–C–C–O–H
| |
H H
Each carbon forms four bonds. Oxygen forms two bonds (one with H, one with C) and has two lone pairs.
2. Dimethyl Ether (CH₃OCH₃) Electron Dot Structure:
H H
| |
H–C–O–C–H
| |
H H
Oxygen in the center forms two single bonds (each with a carbon) and has two lone pairs.
Explanation:
C₂H₆O represents a molecular formula containing two carbon atoms, six hydrogen atoms, and one oxygen atom. This formula has two distinct structural isomers with different physical and chemical properties due to the arrangement of atoms.
The first isomer is ethanol, a type of alcohol. It has a hydroxyl group (–OH) bonded to a carbon atom. Ethanol has a structure where a methyl group (CH₃) is bonded to a methylene group (CH₂), which is then bonded to a hydroxyl group. Each carbon follows the octet rule by forming four covalent bonds, and the oxygen atom forms two single bonds and retains two lone pairs of electrons. This structure allows ethanol to form hydrogen bonds, making it soluble in water and giving it a relatively high boiling point.
The second isomer is dimethyl ether, which is an ether compound. In this structure, the oxygen atom is bonded between two methyl groups (CH₃–O–CH₃). Oxygen again follows the octet rule with two single bonds and two lone pairs. However, dimethyl ether does not have an –OH group, so it cannot form hydrogen bonds like ethanol. As a result, it has lower boiling point and different solubility properties.
Despite having the same molecular formula, ethanol and dimethyl ether are examples of functional group isomers, which differ in the type of functional group present. The electron dot structures highlight how atom arrangement affects chemical behavior.